package design.a4_singleton;

/**
 * 使用类的内部类
 */
public class Singleton_4 {

	private static class SingletonHolder {
		private static Singleton_4 instance = new Singleton_4();
	}

	private Singleton_4() {

	}

	public static Singleton_4 getInstance() {
		return SingletonHolder.instance;
	}

}
